iOS 获取当前时间 年、月、日、周几

    NSDate * nowDate = [NSDate new];

    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSUInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit;

    NSArray * weekTitleArray = @[@"周日",@"周一",@"周二",@"周三",@"周四",@"周五",@"周六"];

    NSArray * monthTitleArray = @[@"一月",@"二月",@"三月",@"四月",@"五月",@"六月",@"七月",@"八月",@"九月",@"十月",@"十一月",@"十二月"];

    NSDateComponents *dateComponent = [calendar components:unitFlags fromDate:nowDate];

    headerView.monthLabel.text = monthTitleArray[[dateComponent month] - 1];

    

    headerView.weekLabel.text = weekTitleArray[[dateComponent weekday] - 1];

    NSInteger day = [dateComponent day];

    headerView.dateLabel.text = (day < 10 ? [NSString stringWithFormat:@"0%ld",day] : [NSString stringWithFormat:@"%ld",day]);